Brake-magnet-demagnetizing device.



E. L. GALE, Sm. BRAKE MAGNETDEMAGNE-TIZING DEVICE- APPLICATION FILEDJULY 14, 1910.

1 ,152,50 1, Patented Sept. 7, 1915.

Suva vufo z i'iniTED STATES tFICE.

ERNEST L. GALE, SR, 013 YON 'K ERS, NEW YORK, ASSIGNOB TO OTI S ELEVATORCOM IPANY, OF JERSEY CITY, NEW JERSEY,- A COEPORATION 01* NEW JERSEY.

. BRAKE-MAGNET-DEMAGNETIZING DEVICE.

Specification of Letters Patent.

Application filed July 14, 1910. Serial No. 571,899.

State of New York, have invented a new and useful Improvement in Brale-lllagnet- DemagnetizingDevices, of which the tollowing is aspecification.

My invention relates to a demagnetizing device. It is more particularlydesignated and described as a brake demagnetizing device for analternating current brake and is shown in connection with elevator aps.

paratus.

()ne of the objects of the invention is to provide means fordemagnetizing a magnet after the energizing circuit is cut oil.

A further object is automatically to open the demagnetizing circuit whenthe magnet has been deinagnetized.

' I In the accon'ipanying drawing-- a motor M and a traction drum l) areshown, operative in the ordinary way to-raise and lower the-ear C andthe counterweight W'. The supplying of current to the motor is effectedby means of the reversing switches it and it which are controlled by theswitch K in the elevator car C.

The brake B is preferably of the type shown, in which the magnetwindings l) are connected in parallel with the motor M and the brakepulley 3 is located on the motor shaft The cores (5 are secured to thebrake levers 4:, and the brake shoes 5 are I adapted to bear upon thebrake pulley 3.

Brake windings 9 are wound about the magnet core 10, and when energizingcur- .rent flows in the brake windings the cores (5 are drawn inwardly.1M :rod ,7 passes through the upper extremities ot the brake levers andthe springs 8 mounted thereon are operative to apply the brake shoes 5to the brake pulley. When, however; th magnet cores (3* are drawninwardly the pressure of the; springs 8 is overcome upperextremitiesotthebrake levers 1 'moved apart amlthe'brake pulley is freeheJbralce shoes This movement apart I brake, levers is relied upon toopera'te it in circuit"closiugidevices? at the exnity' ot'a'iach brakeleverkl are pivotally i'ndu'uted a bell crank lever 12 and a rod 11,

each rod being attached to the opposite bell crank lever. These levers12 are operative to join the contacts 13 and 14; when the Patented Sept.'7, 1915.

brake levers 4C are moved apart. This action closes circuits from themains through the resistances 15 and 15 to the points 16 and 16respectively, and in the ordinary energization and operation of thebrake has no appreciable eti'ect, smce the resistances l5 and 15 arehigh enough to restrict the flow of too much current. If'the contactslilanddl are joined while the reversing switch it IS closed, theresistances 15 and 15 are each connected across the mains,

but if the reversing switch R is closed when the contacts 13 and ii arejoined, the

resistances are short-eircuited and receive practically no current. Theusefulness and effect of my invention become. apparent when there issullicient residual magnetism energized position even after theenergizing current for the motor and brake has been cut oil. In such anevent it is evident that it the elevator car C is heavily loaded, itwill tend to fall since there is no brake to restrain such tendency. Butif the cores (3 are so attracted and held, the contacts 13, -1-t arejoined by the operation of the bell crank levers l2, anddeniagnetizingcircuits are closed through the brake windings 9. These circuits may betraced from the supply mains through the resistances 15, 15' tothepoints 16, 1.6; thence through the brake windings 9 and by way ofconductor 17 t0 the common wire main. Thus it is seen that whenever themagnetcores are magnetically held after the energizing current has beencut cit, a circuit is made eli'ective to demagnetize the brake magnetand magnet cores of residual magnetism.

The theory of operation involved in the demagnetization of the brakemagnet is briefly as follows: As the brake magnet is excited by analternatingcurrent, the magnetism fluctuates rapidly, passingperiodireverse direction and back to zero, etc.

'lhat' is,'tl .e magnetism responds to the ex citing current, and whenthe circuit for the latter is opened the magnetic flux and con sequcntlythe residual magnetism will depend on-the phase of the exciting currentat the instant the circuit is broken. When therefore the reversingswitch It or R is opened the residual. magnetism in the brake magnet mayor may not be suflicient to hold the brakes otf and the switches 13 and1% closed. Assuming the residual magnetism is sullicient to hold theseswitches 13 and 1st closed, current flows in the demagnetizing circuitsas soon as the reversing switch is opened. This current, owing to thehigh resistances l5, 15, in the circuits, is weak and its magnetizingpower insutlicient to hold the brake off, but when opposed to theresidual magnetism is ample to reduce the latter and release the brake.

A further feature of my invention consists in the opening of thisdemaguetizing circuit after the brake has been demagnetizcd. This isetlected by the springs 8 which press the brake levers together, therebymoving the bell crank levers 12 to separate the contacts 13 and l-t.

It is evident that my invention is etlective automatically to close ademagnet-izing circuit, or circuits, through the brake windings, and toopen the said circuit when its object has been attained. The specialadaptation and application to ele'ator service has been pointed out. Itis to be understood however, that I wish not to be specifically limitedto the embodiment herein disclosed, for it is evident that those skilledin the arts to which the invention appertains may make various changeswithout departing from the spirit or scope of the invention.

What I claim and desire to secure by Letters latent of the United Statesis:

1. The combination of an electromagnet and its armature, an energizingcircuit there'lor, a switch to open and close the said circuit. andautomatic means controlled by said electromagnet to supply adeiincrgizing current only when said switch is opened and thereby reducethe residual magnetism and release the magnet armature.

The con'ibination of an electromagnet and its armature, an energizingcircuit therefor, a switch to, open and close the said circuit, and aden'iagnetizing circuit controlled by the said switch and electromagnetto ell'ect the release of the armature.

3. The combination of an alternating cui rentelectromagnetand itsarmature, circuit connections therefor, a switch to open and close thecircuit, and automatic mganscoin trolled by the electromagnefl andrendered active by the opening of said switch to demagnetize theelectroinagnet and releaseits armature.

t. The combination of an alternating current elertr inagnet and itsarmature, circuit connections tlnsretor, a switch to open and close. thecircuit, and means controlled by said. switch and by the armature toeffect the demagnetization and release of the said armatureshonld itfail to releaseupontheopen- 'ing oftlies'witcbi 5. The combination ofancglectromagnet and its armature, an energizing circuit therefor, aswitch to open and close the said circuit, and means controlled by saidarmature and rendered active upon the opening of said switch to elfectthe release of the armature upon its failure to release when the saidswitch is opened.

(3. The eombinationwith a magnet having a movable core, of an energizingcircuit for the magnet, means for opening and closing.

said circuit, and means for automatically rendering effective analternating current circuit through the magnet to demagnetize the magnetonly when the residual magnetism retains the core in its energizedposition after the energizing circuit is opened.

7. The combination with a magnet having movable cores, ot' an energizingcircuit for the magnet, means for opening and closing said circuit, ademagnetizing circuit for said magnet, contacts for maintaining saiddemagnetizing circuit through the magnet winding when residual magnetismretains the cores in an energized position after the energizing circuitis opened and means for automatically opening said contacts to interruptthe demagnetizing circuit after the demagnetization of the magnet ofresidual magnetism.

8. The combination of an alternating current magnet having a movablecore: a normally open demagnetizing circuit for the magnet winding, andmeans dependent upon the position of the core to effect the closure ofsaid circuit.

9. The combination of an alternating current brake magnet,supplyingmains therefor, resistance with one terminal connected to the mains,energizing circuits, a switch for opening and closingsaid energizingcircuits, and circuit closing devices operated by the magnet whenenergized to short-circuit theresistance and to make the resistanceeffective only when the magnet cores are attracted after the energizingcircuits have been opened.

10. The combination of an alternating current bi'ake magnet with movablecores, current supply mains there/for, circuits from the mains to themagnet, a switch for opening and closing said circuits, resistance withone terminal connected to the mains, and means controlled by the magnetto shortcircuit the resistance through the switch when the magnet isenergized and to render the resistance effective in demagnetizing themagnet only when the magnet cores are attracted after the said switchhas been opened.

11. The combination with an alternating current electromagnet having amovable core, an operating circuit therefor, of means controlled by thesaid magnet for maintaining a neutralizing influence upon said core toprevent residual magnetization thereof while the magnet is in operatedposition with its operating circuit opened.

12. The combination with an alternating current electromagnet having amovable core, an operating circuit therefor, of means controlled. by thewinding of said magnet for maintaining a neutralizing influence uponsaid core to prevent residual magnetization thereof while the magnet isin operated position and its operating circuit opened.

13. The combination with an alternating current electromagnet havingrelatively movable members and an energizing winding for bringing saidmembers together, an operating circuit for the winding, of auto maticmeans controlled by the magnet for reducing the current through saidwinding and preventing said members from sticking together when theoperating circuit of the magnet is not effective.

1-4:. The combination with an alternating current electromagnet havingnormal-1y separated magnet cores, an operating circuit for said magnetfor eifecting a relative movement of said cores toward each other, and.means controlled by said magnet cores for passing a small currentthrough the winding of said magnet to overcome the residualmagnetization of said cores when the current in the operating circuit isreduced.

15. The combination with an alternating current clectron'iagnet havingnormally sepa ated member. and an energizing winding for bringing saidmembers together, an operating circuit for said winding, of ademagnetizing circuit controlled by the magnet and containing apredetermined amount of resistance to limit the current through thewinding and eliminate the tendency of the members to stick togetherafter the operating circuit is opened.

16. The combination with an alternating current electromagnct havingnormally separated members, a switch foreclosing a circuit through thewinding of the electromagnet to bring the members together, and meanscontrolled by the said switch, and dependent upon the position of thesaid members for closing a circuit containing resistance or reactancefor the purpose of demagnetizing the said members.

l7. The combination with an alternating current electromagnet havingnormally separated members, a switch for closing a circuit through thewinding of the electromagnet to bring the members together, and meanscontrolled by the said switch and dependent upon the position of thesaid members for establishing a neutralizing influence upon the membersto overcome the residual magnetism of the said members.

18. The combination with an alternating current magnet having normallyseparated core members, means for closing a circuit through the windingof the magnet to move the core members together,and means controlled bysaid. members and circuit closing means for reducing the current in saidmagnet winding to overcome the residual magnetization of the said coremembers.

19. The combination with an alternating current magnet having normallyseparated core members, means for closing a circuit through the windingof the magnet to move the core members together, and means controlled bysaid members and circuit closing means for permitting a smalldemagnetizing current in said magnet winding to overcome the residualmagnetization of the said core members 20. The combination with analternating current magnet having normally separated core members, meansfor closing a circuit through the winding of the magnet to move the coremembers together, and means controlled by said members for establishinga circuit containing a predetermined amount of resistance therein insaid magnet winding to eliminate the tendency of the said core membersto stick together.

21. The combinationv with an alternating current magnet having normallyseparated core members, means for closing a circuit through the windingof the magnet to move the core members together, and means controlled bythe core members for closing a circuit containing resistance orreactance through the said magnet winding to prevent residualmagnetization of the core members when the circuit closing means is inopen position.

22. The combination with an alternating current electromagnet, amagnetizing circuit therefor, and an additional circuit controlled bythe said magnet for demagnetizin'g the.

latter upon the interruption of the magnetizing circuit. v e Thecombination with an alternating current electromagnet, of ademagne'tizing circuit therefor, and means controlled by the magnet foropening and closing said circuit. I In testimony whereof, I have signedmy name to this specification in the presence of two subscribingwitnesses.

ERNEST L. GALE, SR. Witnesses:

GEORGE D. Rosie, EDWARD d. Srnm.

